Flashcards and Answers – Test on Exam 1 –

more significant because compressing a gas decreases the average distance between the particles in the gas which

less significant because increasing the temperature of a gas increases the thermal energy of the particles in the gas which decreases the effect intermolecular attractive forces have on properties of gas.

Argon would be predicted to behave more like an ideal gas at high pressures since the van der Waals constants for argon are less than those for carbon dioxide, argon has weaker intermolecular attractive forces than carbon dioxide and has a smaller volume.

H2S –> bent = polar
PF3 –> trigonal pyramidal = polar
CS2 –> linear = non polar
CBr4 –> tetrahedral = non polar

Polar Molecule –> dispersion forces, dipole-dipole

Polar w/ H-O –> dispersion forces, dipole-dipole, hydrogen bonds

Non Polar –> dispersion forces

a measure of how readily electrons in an atom or molecule move in response to the presence of an instantaneous dipole

Antimony (Sb) because it’s valence electrons are farthest from the nucleus and least tightly held.

Polarizability increases as the # of electrons increases:

CH4 < SiH4 < SiCl4 < GeBr4

The forces of attraction between ammonia molecules are dispersion forces, dipole-dipole interactions and hydrogen bonds the NH3s would be bonded with a hydrogen since hydrogen bonds are the strongest force

The forces of attraction between H2CO molecules are dispersion forces and dipole-dipole which means the attraction would have to be an attractive dipole-dipole meaning the O is facing the C on the other molecule

The only force between these two molecules would be dispersion so they would just have to be beside each other in the greatest possible surface are of contact.

For gases deviation from ideal behavior at low temperatures arises form intermolecular forces. The stronger the intermolecular forces, the greater the deviation from ideal behavior. All 3 of the molecules are non polar so you only have to focus on the strength of their dispersion forces. The heaviest molecule will have the strongest dispersion forces because dispersion forces increase with increasing molar mass which means that Br2 would deviate most.

solids > liquids > gases

gases < liquids < solids

Gasses are the most easy to compress because the particles are far apart and their is much empty space.

HF has dispersion forces, dipole-dipole and hydrogen bonds while HCl only has dispersion forces and dipole-dipole which means that HF will have the higher boiling point since it has the stronger intermolecular forces of hydrogen bonds.

Both of the compounds are polar and have the same intermolecular forces but because the molar mass of CHBr3 is greater that CHCl3 (more electrons) than CHBr3 will have stronger dispersion forces and therefore a higher boiling point.

1-Propanal can form hydrogen bonds because of it’s OH on the end while ethyl methyl cannot which means that 1-Propanal will have stronger intermolecular forces and therefore a higher boiling point.

The stronger the intermolecular attractive forces the greater the value of delta H Vaporization. Also when the intermolecular forces are the same between two molecules, the one with the greater mass (more electrons) will have the stronger intermolecular force. Therefore the ranking of delta H vaporization is:

CH4 < CH3CH3 < CH2Cl2 < CH3OH

Proposal only has dispersion forces and dipole-dipole interactions while 1- Propanal has both of these plus hydrogen bonds which means that Propanal will evaporate faster since it has weaker dispersion forces.

1) mass of water = (1 mL)(1 g/mL) = 100. g

2) moles of water = (100. g)(1/18.02g) = 5.55 mol

3) q = n x delatHvap

q = (5.55 mol)(4.07 kj/mol) = 226 kj

Process:
1. Cool steam from 145 C to 100 C
2. Condense steam at 100 C
3. Cool water from 100 C to 0 C
4. Freeze water at 0 C
5. Cool ice from 0 C to -50 C

= 57.8 kj

Fe because it is an atomic solid held together by metallic bonding.

KCL because it is an ionic solid.

Ti because it is an atomic solid held together by metallic bonding.

H2O because it is capable of hydrogen bonding

Metallic bonds = high melting point
Ionic Solids = medium melting point
Hydrogent Bonding = high melting point

In graphite, carbon atoms are arranged in sheets. Within each sheet, the atoms are covalently bonded to each other by a network of sigma and pi bonds. The electrons in the extended pi network within a sheet can flow which makes graphite a goo electrical conductor in the direction of the plane sheets. In diamond, each carbon atom forms four covalent bonds to four other carbon atoms in a tetrahedral geometry. The electrons in diamond are confined to the covalent bonds and are not free to flow = no electricity.

LiBr –> is an ionic compound which dissolves best in water because of ion-dipole attractive forces

CH3OH –> is a polar compound which dissolves in water because of hydrogen bonding interactions

CH3(CH2)CH2OH –> has a long carbon chain that is hydrophobic which means that it would dissolve in carbon tetrachloride because of dispersion of forces.

Diethyl Ether would be more soluble because it is polar and is able to have hydrogen bonding interactions while Toluene is non polar.

Even though they are both polar, acetone would be more soluble because it can have hydrogen bonding with water while chloroform can not.

Since benzene is non polar, Cyclohexane would dissolve best because it is also non polar while Methanol is polar.

I2 would dissolve best since it is non polar and so is benzene while MgCl2 is polar.

Molality = moles of solute/ moles of solvent –> 12.6 m

Mole Fraction = moles of solute/ total moles –> .185

Molarity = mass/density –> 9.79 M

– Delta H Lattice + Delta H Hydration

The more negative the Delta H Hydration, the stronger the ion-dipole

Sgas = kh x Pgas

kh = contant 3.4 x 10^-2 M/atm

Psolution = X hexaneP hexan

X hexane = moles of hexane/ (moles hexane + moles naphthalene)

Delta Tf = Kfm

Osmotic Pressure = MRT

M= .08206 L atm/mol K